1. Field of the Invention
The present invention relates to an air conditioner for a hybrid vehicle having an engine and an electrical motor for running the vehicle.
2. Description of Related Art
In a conventional hybrid vehicle disclosed in JP-A-2000-270401, there is provided with an air conditioning unit for performing air-conditioning operation in a passenger compartment by using electrical power supplied from a battery. Further, when a residual charging degree of the battery becomes equal to or lower than a charging-starting target value (target degree), the battery is charged by driving a generator using a vehicle engine. While the vehicle is stopped or runs with a low load, the engine is stopped when the residual charging degree of the battery is higher than the charging target value.
However, in the above-described air conditioning unit, the battery is charged only when the residual charging degree becomes equal to or lower than the target degree, regardless the operation state of the engine. Therefore, even in a case where the vehicle is running while the engine is stopped, the operation of the engine is started only for charging the battery when the residual charging degree becomes equal to or lower than the target degree. When the vehicle engine is frequently driven only for charging the battery as in this manner, fuel consumption efficiency cannot be sufficiently improved.